Mukesh Singh is the younger brother of Ram Singh. Both were charged, along with three other men and a juvenile, in the gang rape and murder of a 23-year-old woman on a moving bus in New Delhi in December.

The Singh family moved to New Delhi from their native village in the western Indian state of Rajasthan in the early 1990s. Both brothers worked as builders on houses and roads and then became drivers, according to a relative. They lived in the south Delhi slum of Ravi Dass Camp, where neighbors described them as rowdy, heavy drinkers who often disturbed the peace in the neighborhood.

Mukesh Singh, in his statement to court in July, admitted to driving the bus on Dec. 16, but said he was not aware of the attack taking place and pleaded not guilty to charges including kidnapping, rape and murder in a special fast-track court in the capital.

He was devastated by the death of his brother—found dead in his jail cell in March—according to his current lawyer, V.K. Anand. (Mukesh Singh has changed lawyers three times since proceedings began.) Prison authorities say the death was suicide by hanging; his family and lawyer say it was murder. An investigation continues.

Mr. Anand has claimed that Mukesh Singh was tortured by police in jail after his arrest. Police deny the ill treatment.

Vinay Sharma

Age at time of arrest: 20

Plea: Not guilty

Verdict: Guilty

Sentence: Death

Vinay Sharma, one of the men accused of gang-raping and murdering a young physiotherapy student last year, is described by his family as shy and simple—though he’s the only high-school graduate among the defendants.

In June, from jail, the 20-year-old took first-year exams for Delhi University’s bachelor of arts degree—a generic course he enrolled in prior to his arrest. Before that, in April, he took an examination for an entry-level job with the Indian Air Force, also from prison. The results for both are awaited.

To help him better prepare for the examinations, his lawyer, A.P. Singh, hired a tutor who visited jail five times a week. Mr. Singh also requested fresh fruit, milk and almonds for his client—to improve his concentration. Such food is not normally on offer to prisoners, but jail authorities agreed to provide them in this case.

But Mr. Singh alleges Mr. Sharma was also beaten and served poisoned food in prison, which officials denied.

A gym assistant and a keen bodybuilder, before his arrest Mr. Sharma took protein supplements and watched his diet closely, avoiding rice because of the calories, his mother said in an interview with The Wall Street Journal in January. In his free time, she said, he watched cartoons and played marbles with his 13-year-old brother.

When one of his younger sisters heard the sentence given to her brother on Tuesday she told The Wall Street Journal that she felt terrible. Ilu, Vinay’s teenage sister, said: “People ask us to leave this neighborhood. I think it will be difficult for us to live here.”

Pawan Gupta

Age at time of arrest: 19

Plea: Not guilty

Verdict: Guilty

Sentence: Death

Mr. Gupta’s lawyer, Vivek Sharma, has said his client is innocent of all charges.

Pawan Gupta, a fruit seller, is among the six accused in the rape and murder of the 23-year-old woman in Delhi in December. Mr. Gupta lives in Ravi Dass Camp, a slum also home to three other defendants: Vinay Sharma and Mukesh and Ram Singh.

Mr. Gupta lives with his parents, also fruit sellers. The family has lived in the slum for around a year and a half.

Akshay Kumar Singh

Age at time of arrest: 28

Plea: Not guilty

Verdict: Guilty

Sentence: Death

Bus cleaner Akshay Kumar, one of the defendants in the gang rape and murder trial, is the youngest of three sons of a small farmer in India’s eastern state of Bihar.

Mr. Kumar left school after the seventh grade and in 2010 married Punita Devi; they have a young son. Last summer he moved to Delhi, where he befriended a driver named Ram Singh at a bus-repair shop. He soon began working on Mr. Singh’s bus so he could learn to drive, according to police.

He worked as a cleaner on private buses in Delhi and police say he was present on the bus on the night of Dec. 16, when the alleged attack took place. His lawyer, A.P. Singh, denies Mr. Kumar was on the bus.

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